Systems and methods for coexistence of wlan and bluetooth networks

ABSTRACT

Systems and methods for coexistence of WLAN and Bluetooth networks are described. At least one embodiment includes a method for operating a wireless device in both a 802.11 network and a Bluetooth network. In accordance with some embodiments, the method comprises monitoring transmission of Synchronous Connection Oriented (SCO) slots over the Bluetooth network, informing an access point (AP) in the 802.11 network not to transmit to the device before the end of an SCO slot, transmitting a power save trigger to the AP to retrieve buffered data from the AP, and transmitting data to the AP.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims priority to, and the benefit of, U.S.Provisional Patent Application entitled, “Bluetooth Coex Scenarios(Using 802.1 1 NAVs to Prevent Collisions between Access Point Beaconsor Data Frame Transmission and Bluetooth Transmissions),” having Ser.No. 60/861,799, filed on Nov. 30, 2006, which is incorporated byreference in its entirety.

TECHNICAL FIELD

The present disclosure generally relates to wireless communications andmore particularly relates to systems and methods for allowingcoexistence of WLAN and Bluetooth networks.

BACKGROUND

Wireless protocols such as Bluetooth and IEEE 802.11 define the logicalinterconnections of portable terminals having a variety of types ofcommunication capabilities to host computers. The logicalinterconnections are based upon an infrastructure in which at least someof the terminals are capable of communicating wirelessly with anotherdevice when located within a predetermined range.

The Bluetooth standard provides a way to connect and exchangeinformation between devices such as mobile phones, wireless headsets,laptops, PCs, printers, digital cameras, etc. over a secure, globallyunlicensed short-range radio frequency. The protocol operates in thelicense-free ISM (industrial, scientific and medical) band from2.4-2.4835 GHz. Over time, Bluetooth has become popular for suchapplications as wireless communication/control between mobile phones anda hands-free headsets. Other applications include wireless networkingbetween PCs in addition to networking between PCs and output devicessuch as mouse devices and printers.

The IEEE standard for 802.11 is set out in “Wireless LAN Medium AccessControl (MAC) and Physical Layer (PHY) Specifications” and is availablefrom the IEEE Standards Department, Piscataway, N.J. The 802.11 standardpermits either IR or RF communications at 1 Mbps, 2 Mbps and higher datarates and performs a medium access technique similar to carrier sensemultiple access/collision avoidance (CSMA/CA). The 802.11 standardfurther provides a power-save mode for battery-operated mobile stations,seamless roaming in a full cellular network, high throughput operation,diverse antenna systems designed to eliminate “dead spots,” and an easyinterface to existing network infrastructures.

As both Bluetooth and 802.11 WLANs share the same unlicensed frequencyband (i.e., the 2.4 GHz band), this can lead to collisions between thetwo networks. Accordingly, various needs exist in the industry toaddress the aforementioned deficiencies and inadequacies.

SUMMARY

Briefly described, one embodiment, among others, includes a method foroperating a wireless device in both a 802.11 network and a Bluetoothnetwork. In accordance with some embodiments, the method comprisesmonitoring transmission of Synchronous Connection Oriented (SCO) slotsover the Bluetooth network, informing an access point (AP) in the 802.11network not to transmit to the device before the end of an SCO slot,transmitting a power save trigger to the AP to retrieve buffered datafrom the AP, and transmitting data to the AP.

Another embodiment includes a wireless communication device capable ofoperating in both a 802.11-based network and a Bluetooth network. Insome embodiments, the device comprises a timer module and acommunications module. The timer module is configured to monitor anddetermine the timing of Synchronous Connection Oriented (SCO) slots. Thecommunications module is configured to notify an access point (AP) notto transmit data based on the timing of the SCO slots and transmit powersave trigger frames to retrieve data from the AP.

Yet another embodiment includes a method for operating a wireless devicein both a 802.11 network and a Bluetooth network. According to someembodiments, the method comprises determining the beginning of a firstSCO slot, setting a Network Allocation Vector (NAV) which ends beforethe end of the first SCO slot at an access point (AP) in the 802.11network so that the AP stops transmitting data to the device,transmitting a power save trigger to the AP to retrieve buffered datafrom the AP, transmitting data to the AP, and receiving data from the APat the end of the first SCO slot.

Other systems, methods, features, and advantages of the presentdisclosure will be or become apparent to one with skill in the art uponexamination of the following drawings and detailed description. It isintended that all such additional systems, methods, features, andadvantages be included within this description, be within the scope ofthe present disclosure, and be protected by the accompanying claims.

BRIEF DESCRIPTION OF THE DRAWINGS

Many aspects of the disclosure can be better understood with referenceto the following drawings. The components in the drawings are notnecessarily to scale, emphasis instead being placed upon clearlyillustrating the principles of the present disclosure. Moreover, in thedrawings, like reference numerals designate corresponding partsthroughout the several views.

FIG. 1A depicts an embodiment of a system configured to coexist in botha WLAN and a Bluetooth network.

FIG. 1B illustrates various components of the communications moduledepicted in FIG. 1A.

FIG. 2 depicts an embodiment of a method for coexisting in both a WLANand a Bluetooth network.

FIG. 3 illustrates an embodiment of the wireless device shown in FIG. 1Afor executing the various steps depicted in FIG. 2.

FIGS. 4-7 provide non-limiting examples where exemplary methods forcoexisting in both a WLAN and a Bluetooth environment are incorporated.

FIGS. 4A-C illustrate transmissions in both the Bluetooth environmentand the WLAN where the PHY rate in the WLAN is 1 Mbps.

FIGS. 5A-C illustrate transmissions where the PHY rate in the WLANnetwork is 2 Mbps.

FIGS. 6A-C illustrate transmissions where the PHY rate in the WLANnetwork is 6 Mbps.

FIGS. 7A-C illustrate transmissions where the PHY rate in the WLANnetwork is 54 Mbps.

DETAILED DESCRIPTION

Having summarized various aspects of the present disclosure, referencewill now be made in detail to the description of the disclosure asillustrated in the drawings. While the disclosure will be described inconnection with these drawings, there is no intent to limit it to theembodiment or embodiments disclosed herein. On the contrary, the intentis to cover all alternatives, modifications and equivalents includedwithin the spirit and scope of the disclosure as defined by the appendedclaims.

As discussed earlier, the Bluetooth and 802.11 WLANs share the sameunlicensed frequency band, in particular the 2.4 GHz band. Consequently,this can lead to collisions between the two networks. Furthermore, oneapplication that relies on the coexistence of Bluetooth and WLAN devicesinvolves placing a voice call using a Bluetooth wireless earpiece and ahandheld device (via SCO slots), where the voice data is then routedover a WLAN to an access point (AP) and ultimately through a wired longdistance infrastructure, such as the Internet.

The IEEE 802.15.2-2003 Recommended Practices addresses the issue ofcoexistence of Wireless Personal Area Networks (WPAN) with otherwireless devices operating in unlicensed frequency bands such as thoseutilized by wireless local area networks (WLAN). The IEEE 802.15Coexistence Task Group 2 (TG2) developed a Recommended Practices tofacilitate coexistence of WPAN and WLAN. The Task Group specificallydeveloped a Coexistence Model to quantify the mutual interference of aWLAN and a WPAN. The Task Group also developed a set of CoexistenceMechanisms to facilitate coexistence of WLAN and WPAN devices.

The IEEE 802.15.2 Recommended Practices define an interface betweencollocated Bluetooth and WLAN units, where each Bluetooth unit canrequest channel access and provide an indication of activity. It shouldbe noted that through the PTA (Packet Traffic Arbitration) interface,the WLAN may determine and predict the timing of Bluetooth SCO(Synchronous Connection Oriented) slots, which are used to convey highpriority traffic such as voice. This is just one technique and otherconfigurations in which the WLAN unit may determine or predict thetiming of SCO slots associated with Bluetooth units may be possible.Based on the SCO slot timing obtained via the PTA interface, the WLANclient can time its transmissions so as to not interfere with the SCOslows. However, one perceived shortcoming with this approach is that thetiming of transmissions from the AP is beyond the immediate control ofthe WLAN client.

One approach to addressing this apparent shortcoming is throughutilization of polled power conservation methods where legacy PSM(PS-Poll or CAM/PSM switching) and U-APSD (Unscheduled AsynchronousPower Save Delivery) are utilized to influence the timing oftransmissions from the AP. The timing associated with the PSM (PowerSave Mode) trigger frame (trigger frame for U-APSD, PS-Poll frame forlegacy PSM, or a frame with the PM bit not set for CAM/PSM (ContinuallyAwake Mode/Power Save Mode) switching) provides approximate timing ofany downlink transmission from the AP down to the client as the AP willrefrain from transmitting to clients currently in power save mode unlessthe clients send a PSM trigger frame.

Based on this method, the time between successive SCO slots is used forthe trigger frame, the uplink voice frame, the AP turnaround time, andthe downlink voice frame. For low PHY rates on the WLAN, the timerequired for these events will exceed the time between SCO slots,effectively barring these PHY rates for use in this scenario. Inside theSCO slots, Bluetooth devices use high quality voice transmissions. Thismay comprise HV3 (High Quality Voice) over a SCO link, for instance.With HV3,the uplink and downlink SCO slots take 1250 μs to completewhere the time between SCO slots is 2500 μs. Further details regardinguse of PSM frames to influence the timing of downlink WLAN transmissionsfor the purpose of avoiding conflicts with SCO slots is described inU.S. patent application Ser. No. 10/861,064 (Pub. No. 2005/0025174),filed Jun. 4, 2004, herein incorporated by reference in its entirety.

As known by those skilled in the art, the Network Allocation Vector(NAV) relates to a method for avoiding collisions in a sharedtransmission medium. Each client that wants to transmit data using theshared medium may first perform a RTS (Request to Send) with a NAV thatindicates the time required to complete the desired transmission. If nocollision is detected and if a clear-to-send (CTS) packet is sent, theshared medium is considered to be allocated to the client that generatedthe RTS during the time specified by the NAV. The RTS and the CTS eachset a NAV locally around the respective senders of the RTS and the CTS.Generally, for 802.11, the NAV can be reset by the AP through thetransmission of a Contention Free End (CF-End) frame, but for 802.11n,clients are also allowed to reset a NAV by transmitting a CF-End frame.

Embodiments of systems and methods described herein seek to address theperceived shortcomings discussed earlier by configuring the WLAN clientto indirectly influence the time of transmissions from the AP. Accordingto exemplary embodiments, the transmission of PSM trigger frames aretimed such that uplink voice transmissions over the WLAN may beconducted before the beginning of the next SCO slot. For alternativeembodiments, this may involve sending a PS-Poll trigger frame or U-APSDtrigger frame. As part of the uplink voice and trigger transmissions, ashort frame is included which sets a NAV at the AP that ends after thepending SCO slot. NAV protection uses the IEEE 802.11 virtual carriersense mechanism to cause stations that detect the frame to set theirinternal carrier sense to the “busy” state, even if they do not senseradio frequency energy during the NAV protection interval.

Accordingly, an exemplary method for coexisting in both a 802.11-basednetwork and a Bluetooth network comprises monitoring transmission of SCOslots sent over the Bluetooth network to determine timing of the SCOslots. The method further comprises transmitting a power save triggerframe according to the determined timing and setting a NAV to stoptransmission from an access point. In some embodiments, the power savetrigger frame is transmitted from a client to the access point betweenSCO slots, uplink transmission over the 802.11-based network takes placebetween SCO slots, and downlink transmission begins after the NAVexpires.

By setting the NAV to end after the pending SCO slot, the response whichincludes buffered data from the AP is delayed until after the pendingSCO slot. Notably, each WLAN voice transmission (both uplink anddownlink) can then utilize almost the entire period between successiveSCO slots, while the AP turnaround time is timed to coincide with theSCO slot itself. As such, it should be noted that more time becomesavailable for actual WLAN transmissions, thereby allowing use of lowerPHY rates and ultimately resulting in better range for the WLAN. Itshould also be noted that to a certain extent, the SCO slot becomesprotected from interference by other WLAN nodes. Finally, it should beemphasized that the AP turnaround time overlapping with the SCO slotincreases the overall efficiency of medium utilization.

Setting a NAV at the AP requires the transmission of a frame which isnot addressed at the AP, and which contains a Duration value inside theMAC header. For some embodiments, this can be a CTS frame addressed atthe client. The CTS is transmitted at a rate that can be decoded by theAP. A lower rate is not required because the main purpose is toinfluence the timing of downlink transmissions at the AP, while settinga NAV in a too large area around the client is avoided. Furthermore,directional PHY mechanisms such as beamforming can be used to furtherfocus setting of the NAV only at the AP. It is also possible that a newmethod is added to the IEEE 802.11 standard (or at WFA (WiFi Alliance)to set a temporary transmission restriction at the AP, which appliesonly to the related client. In this case, the frame should be addressedat the AP. The transmission restriction timing information may even beincluded inside the MAC header of the uplink data frame which istransmitted to the AP.

Reference is now made to FIG. 1A, which depicts an embodiment of asystem configured to coexist in both a WLAN and a Bluetooth network. Inparticular, FIG. 1A illustrates atypical network configuration forcommunicating data between clients via an access point in a WLAN or802.11-based network. As illustrated in the non-limiting example of FIG.1A, a network 140 may be coupled to access point 130. In someembodiments, the network 140 may be the Internet, for example. Theaccess point 130 can be configured to provide wireless communications tovarious wireless devices of clients 110, 120, 150. Depending on theparticular configuration, the clients 110, 120, 150 may be a personalcomputer, a laptop computer, a mobile phone, a Personal DigitalAssistant, and/or other device configured for wirelessly sending and/orreceiving data. Furthermore, the access points 130 may be configured toprovide WIFI services, WiMAX services, wireless SIP services and/orother wireless communication services. As a non-limiting example, theclients 110, 120 may be configured for WIFI communications (including,but not limited to 802.11, 802.11b, 802.11a/b, 802.11g, and/or 802.11n).

FIG. 1A also depicts various Bluetooth devices connected over aBluetooth connection. For purposes of illustration, a printer 180 withan integrated Bluetooth interface is coupled to the client 120, which inaddition to having a WLAN interface, also has a Bluetooth interface.FIG. 1A also depicts a mobile phone 150. The mobile phone 150 may be asmartphone capable of interfacing with both 802.11-based networks andBluetooth-enabled devices such as the wireless earpiece 130 shown. Thesmartphone 150 may, for example, have connectivity to the Internetthrough the WLAN and provide mobile voices services through use of theearpiece 130. In this regard, the smartphone 150 is a client connectedto the same wireless AP 130 that the other two clients 110, 120 areconnected to.

As discussed earlier, one application that relies on the coexistence ofBluetooth and WLAN devices involves placing voice calls using aBluetooth wireless earpiece 130 (such as the one depicted in FIG. 1) anda handheld device 150, where voice data is then routed over a WLAN to anAP 130 and ultimately through a wired long distance infrastructure, suchas the Internet. One such application is voice-over-WLAN (or VOWLAN)which targets laptop computers, cell phones, and PDAs. In such devices,both Bluetooth and WiFi services need to operate simultaneously in thesame device.

In order to coexist in both the WLAN and Bluetooth environments, theclient 120 may include a timer module 160 configured to monitor anddetermine the timing of Synchronous Connection Oriented (SCO) slotstransmitted over the Bluetooth network. The client 120 may furtherinclude a communications module 170 configured to transmit power savetrigger frames according to the timing of SCO slots such that the uplinktransmission over the 802.11-based network ends before the next SCOslot. The modules 160, 170 may be implemented in software, hardware, ora combination of both.

FIG. 1B illustrates various components of the communications moduledepicted in FIG. 1A. In some embodiments, the communications module 170may comprise logic 190 configured to set a Network Allocation Vector(NAV) such that the access point ceases transmission of data. The NAV isset so that the time in which it expires aligns with the end of an SCOslot. The communications module 170 further comprises logic 192configured to send a clear-to-send (CTS) frame which specifies theduration of the NAV. Upon transmission of the CTS frame by logic 192,the NAV is set and expires upon reaching the time specified. Thecommunications module 170 may further comprise logic 194 configured toreceive downlink transmissions between successive SCO slots.

Reference is now made to FIG. 2, which depicts an embodiment of a methodfor coexisting in both a WLAN and a Bluetooth network. Beginning in step210, the transmission of SCO slots sent over the Bluetooth network ismonitored. By monitoring the transmission of SCO slots, timinginformation is derived in step 220. In step 230, power save triggerframes are then transmitted according to the derived timing. A CTS framemay be used to specify the duration of the NAV (step 240). In step 250,a NAV is set so that it expires at the end of an SCO slot. Upon sendingthe CTS frame, uplink data is sent during the time duration between SCOslots so that interference can be avoided between the two protocols(step 260). In addition, transmission of downlink data is timed suchthat it takes place between SCO slots (step 270).

FIG. 3 illustrates an embodiment of the wireless device shown in FIG. 1Afor executing the various steps depicted in FIG. 2. Generally speaking,the client 120 can comprise any one of a wide variety of wired and/orwireless computing devices, such as a desktop computer, portablecomputer, dedicated server computer, multiprocessor computing device,cellular telephone, personal digital assistant (PDA), handheld or penbased computer, embedded appliance and so forth. Irrespective of itsspecific arrangement, the client 120 can, for instance, comprise memory312, a processing device 302, a number of input/output interfaces 304, anetwork interface 306, a display 308, and mass storage 324, wherein eachof these devices are connected across a data bus 310.

Processing device 302 can include any custom made or commerciallyavailable processor, a central processing unit (CPU) or an auxiliaryprocessor among several processors associated with the computing device102, a semiconductor based microprocessor (in the form of a microchip),a macroprocessor, one or more application specific integrated circuits(ASICs), a plurality of suitably configured digital logic gates, andother well known electrical configurations comprising discrete elementsboth individually and in various combinations to coordinate the overalloperation of the computing system.

The memory 312 can include any one of a combination of volatile memoryelements (e.g., random-access memory (RAM, such as DRAM, and SRAM,etc.)) and nonvolatile memory elements (e.g., ROM, hard drive, tape,CDROM, etc.). The memory 312 typically comprises a native operatingsystem 314, one or more native applications, emulation systems, oremulated applications for any of a variety of operating systems and/oremulated hardware platforms, emulated operating systems, etc. Forexample, the applications may include application specific software 122such as the timer module 160 and communications module 170 depicted inFIG. 1. It should be noted, however, that the timer module 160 andcommunications module 170 can also be implemented in hardware or acombination of software and hardware. One of ordinary skill in the artwill appreciate that the memory 312 can, and typically will, compriseother components which have been omitted for purposes of brevity.

Input/output interfaces 304 provide any number of interfaces for theinput and output of data. For example, where the client 120 comprises apersonal computer, these components may interface with user input device304, which may be a keyboard or a mouse. Where the client 120 comprisesa handheld device (e.g., PDA, mobile telephone), these components mayinterface with function keys or buttons, a touch sensitive screen, astylist, etc. Display 308 can comprise a computer monitor or a plasmascreen for a PC or a liquid crystal display (LCD) on a hand held device,for example.

With further reference to FIG. 3, network interface device 306 comprisesvarious components used to transmit and/or receive data over a networkenvironment. By way of example, the network interface 306 may include adevice that can communicate with both inputs and outputs, for instance,a modulator/demodulator (e.g., a modem), wireless (e.g., radio frequency(RF)) transceiver, a telephonic interface, a bridge, a router, networkcard, etc.). The client 120 may further comprise mass storage 326. Forsome embodiments, the mass storage 326 may include a database 328 tostore and manage such data as metadata.

Reference is now made to FIGS. 4A-C, 5A-C, 6A-C, and 7A-C, which providenon-limiting examples where exemplary methods for coexisting in both aWLAN and a Bluetooth environment described earlier are incorporated. Thefigures illustrate use of a PS-Poll trigger frame, a CAM togglingscheme, and a U-APSD trigger frame to indirectly influence the time oftransmissions from the AP. In particular, FIGS. 4A-C illustratetransmissions in both the Bluetooth environment and the WLAN where thePHY rate in the WLAN is 1 Mbps. FIGS. 5A-C illustrate transmissionswhere the PHY rate in the WLAN network is 2 Mbps. FIGS. 6A-C illustratetransmissions where the PHY rate in the WLAN network is 6 Mbps. FIGS.7A-C illustrate transmissions where the PHY rate in the WLAN network is54 Mbps. It should be noted again that the components depicted in thedrawings are not necessarily drawn to scale and emphasis is placed uponclearly illustrating the exemplary embodiments described herein.

In accordance with exemplary embodiments described herein, 802.11compliant devices 110, 120, 150 such as the ones depicted in FIG. 1Aswitch to a power save mode when not engaged in network communication.An access point 130 buffers incoming data for such power-saving 802.11compliant devices 110, 120, 150 and sends a beacon signal after apre-defined time interval indicating the presence of buffered data forthe power-saving 802.11 compliant devices 110, 120, 150. Such devices110, 120, 150 switch from the power save mode to an active mode toreceive and check the beacon signal for any indication of buffered dataat the access point for the device. If there is any indication ofbuffered data at the access point, the device sends a Power Save-Poll(PS-Poll) to the access point 130 requesting the access point 130 tosend the buffered data to the device 110, 120, 150.

The access point 130 responds by transmitting buffered data to thedevice 110, 120, 150. The buffered data is transmitted in the form ofdata frames, which carry an indication of any additional buffered dataat the access point. If there is such an indication, then the device110, 120, 150 transmits another PS-Poll and receives the additionalbuffered data. This process repeats until there is no further indicationof additional buffered data at the access point. Thereafter, the device110, 120, 150 switches back to the power save mode, thereby conservingpower. FIGS. 4A, 5A, 6A, and 7A depict use of the PS-Poll trigger framesfor varying PHY rates ranging from 1 Mbps to 54 Mbps.

With reference to FIG. 4A, when the PHY rate is very low (i.e., on theorder of 1 Mbps), the CTS frame, PS-Poll frame and uplink voicetransmission do not fit between two adjacent HV3 SCO slots (i.e., 2500μs). As such, the CTS 404 and PS-Poll 406 frames are sent one inter-SCOgap earlier, as depicted in FIG. 4A. The device sends a CTS frame 404and a PS-Poll frame 406 to the access point to request the access pointto send buffered data to the device. The access point responds to thePS-Poll frame with an ACK frame after an SIFS (short interframe space)408 delay. During the ensuing inter-SCO gap, the device generates uplinkdata 410.

Uplink transmission 410 takes place in the ensuing gap, and downlinktransmission follows accordingly. It should also be noted that upontransmission of the CTS frame 404, the NAV is set for 3,157 μs andexpires at the end of an SCO slot at time instance 402. During this timeinterval, no traffic is sent from the access point. As noted earlier,the response from the access point, which includes buffered data, isdelayed until after this pending SCO slot. One should note that,depending on the particular configuration, the interval times and/ordata frame times may differ from those described with regard to thefigures shown. Similarly, the amount of data transmitted in a data framemay differ, depending on the particular configuration. The values givenfor these parameters are included for purposes of illustration and arenot intended to limit the scope of this disclosure.

Wireless devices generally have two power consumption modes: ConstantlyAwake Mode (CAM) and Power Save Polling (PSP). Power Save Polling causesthe card to “sleep” on a periodic basis, turning its radio signal off.In CAM, the client adapter is kept powered up continuously so that thereis little lag in message response time. FIGS. 4B, 5B, 6B, and 7Billustrate use of CAM toggling to achieve coexistence of Bluetooth andWLAN VoIP transmissions. With reference to FIG. 4B, the device sends aCTS frame which specifies the duration of the NAV. In the non-limitingexample shown in FIG. 4B, the duration of the NAV is 4,981 μs. Upontransmission of the CTS frame 420, the NAV is set and expires uponreaching the time specified (time instant 422 which aligns with the endof an SCO slot). At this time, the access point generates downlinktraffic to the device. In the next inter-SCO gap after sending the CTS,the device sends uplink data with the PM bit not set so that the AP willsend downlink traffic after expiration of the NAV.

Unscheduled Asynchronous Power Save Delivery (U-APSD) is a power savemechanism for 802.11-based systems in which the communications device110, 120, 150 sends a trigger frame to an access point 130 (for instancean uplink voice frame), which is then acknowledged by the access point130. Transmission of the trigger frame is depicted in FIGS. 4C, 5C, 6C,and 7C. With reference to FIG. 4C, at some time after receiving thetrigger frame 430, the access point responds with the buffered downlinktraffic. The time for the response to begin may take some time, becausethe buffered data may be stored in a portion of the access point'smemory, which may have higher access latency, due to the design of theaccess point and the possibly large amount of data to buffer at theaccess point.

During the turnaround time, the client may remain in a normal operationmode and remain in receive mode until the client receives a responsefrom the AP. On the final buffered downlink frame, the AP may set an EndOf Service Period (EOSP) bit 432, which is an indication for the clientsthat the service period has ended and that it can return to a power savemode, where at least one of the active components utilized during normaloperation is deactivated during a period of communicative inactivity.Similarly, PS-Poll based power saving may operate in a similar fashion,except that there may only be a single downlink Media Access Control(MAC) Protocol Data Unit (MPDU). The timing associated with the triggerframe and the ESOP bit is illustrated in FIGS. 4C, 5C, 6C, and 7C, whichillustrate use of the U-APSD trigger frame to control transmission fromthe access point.

As discussed earlier and as depicted in FIGS. 4A-C, 5A-C, 6A-C, and7A-C, HV3 data frames are sent in a Bluetooth environment at regularintervals of 2500 μs, with the data frames being sent at 1250 μs. Assuch, the duration of each SCO slot is usually long enough for the AP tocollect downlink data from its power-save repository. Notably, theprobability is high that the AP will send the response soon after theend of an SCO slot (i.e., the NAV protected period). Furthermore, theprobability is high that the AP will complete its transmission beforethe start of the next SCO slot, and therefore, collisions are avoided.When the turnaround time of the AP is relatively short and the WLAN PHYrate is relatively high, it is possible for the entire uplink anddownlink VoIP exchange to take place in between two successive inter-SCOgaps. However, in anticipation of the event that the downlinktransmission overlaps with an SCO slot, the uplink transmission and thedownlink transmission may be split across consecutive inter-SCO gaps.

It should be further emphasized that the above-described embodiments aremerely examples of possible implementations. Many variations andmodifications may be made to the above-described embodiments withoutdeparting from the principles of the present disclosure. All suchmodifications and variations are intended to be included herein withinthe scope of this disclosure and protected by the following claims.

1-23. (canceled)
 24. A method for operating a device in both an 802.xnetwork and a second network, comprising: monitoring transmission ofsynchronous connection oriented slots over the second network; informingan access point (AP) in the 802.x network not to transmit to the devicebefore the end of a synchronous connection oriented slot by setting anetwork allocation control at the AP, wherein the network allocationcontrol expires at the end of the synchronous connection oriented slot;transmitting a power save trigger to the AP to retrieve buffered datafrom the AP, wherein the power save trigger is one of a power save poll,a data frame with a power management control, or an unscheduledasynchronous power save trigger, wherein the data frame with the powermanagement control is transmitted in a next-inter synchronous connectionoriented gap after sending clear to send data; and transmitting data tothe AP.
 25. The method of claim 24, wherein the AP sends the buffereddata to the device across consecutive gaps between synchronousconnection oriented slots after the end of a first synchronousconnection oriented slot.
 26. The method of claim 25, wherein the datais a voice frame.
 27. The method of claim 25, wherein informing the APoccurs in an unscheduled period before a second synchronous connectionoriented slot that precedes the first synchronous connection orientedslot.
 28. The method of claim 27, wherein the transmitting of the powersave trigger occurs in the unscheduled period before the secondsynchronous connection oriented slot.
 29. The method of claim 24,wherein the setting the network allocation control comprises sending theclear to send data.
 30. The method of claim 24, wherein the informingthe access point comprises sending timing information to the AP otherthan through the network allocation control, and the AP transmitsdownlink data after expiration of the network allocation control. 31.The method of claim 30, wherein the timing information is conveyed aspart of a media access control of a data frame containing the timinginformation.
 32. The method of claim 24, further comprising sending thedata frame with the power management control set after a thirdsynchronous connection oriented slot, wherein the third synchronousconnection oriented slot occurs after a first synchronous connectionoriented slot.
 33. The method of claim 24, wherein the data comprisesvoice data.
 34. A wireless communication device capable of operating inboth an 802.x network and a second network, the device comprising: atimer module configured to monitor and determine a timing of synchronousconnection slots; and a communications module configured to: notify anaccess point not to transmit data based on the timing of the synchronousconnection slots; and transmit a power save control to retrieve the datafrom the access point, wherein the communications module notifies theaccess point not to transmit the data by setting a network allocationcontrol such that the network allocation control expires at the end of asynchronous connection slot, wherein the power save control is one of apower save poll frame, a data frame with power management data, or anunscheduled asynchronous power save trigger frame, wherein the dataframe with the power management data is transmitted in a next-intersynchronous connection slot gap after sending a clear to send frame. 35.The device of claim 34, wherein the communications module compriseslogic configured to send the clear to send frame over the 802.x network.36. The device of claim 35 wherein the clear to send frame includes aduration field specifying duration of the network allocation control.37. The device of claim 34, wherein the device is configured to supportvoice packets.
 38. The device of claim 37, wherein the voice packets areHigh Quality Voice 3 (HV3) packets.
 39. The device of claim 34, whereinthe synchronous connection slot is a Bluetooth Synchronous ConnectionOriented (SCO) slot, the network allocation control is an 802.x NetworkAllocation Vector (NAV), the power save control is a Power Save-Poll(PS-Poll) frame, a data frame with a power management data is a datafrom with a Power Management (PM) bit not set, and the unscheduledasynchronous power save trigger frame is an Unscheduled AsynchronousPower Save Delivery (U-APSD) trigger frame.
 40. A method for operating awireless device in both an 802.x network and a second network, themethod comprising: determining an end of a first synchronous slot;setting a network allocation control that ends at the same time as theend of the first synchronous slot at an access point (AP) in the 802.xnetwork so that the AP stops transmitting data to the device;transmitting a power save control to the AP to retrieve buffered datafrom the AP, wherein the power save control is one of a power save poll,a data frame with a power management control not set, and an unscheduledasynchronous power control, wherein the data frame with the powermanagement control not set is transmitted in synchronous slot gap aftersending a clear to send control; transmitting data to the AP during aperiod set by the network allocation control and prior to a beginning ofthe first synchronous slot; and receiving other data from the AP afterthe end of the first synchronous slot.
 41. The method of claim 40,wherein setting the network allocation control comprises sending theclear to send control.
 42. The method of claim 40, wherein for theunscheduled asynchronous power control, the AP sets an end of servicecontrol to indicate that the client may enter into a power save mode.43. The method of claim 40, wherein the end of service control is set ona final buffered downlink frame.